Dynamo-electric machine.



FATENTED MAR. 20, .1906.

J. P. MALLBTT. DYNAMO ELECTRIC MACHINE.

APPLICATION FILED MAY 21, 1904.

I I I ll l' gm M fly/I IHI/EHTOR:

John P Max/{605,

UNITED STATES PATENT OFFICE.

JOHN P. MALLETT, OF MADISON, I/VISOONSIN, ASSIGNOR TO NORTHERN ELEO"R1OAL MANUFACTURING COMPANY, A CORPORATION OF WIS- CON SIN DYNAMO-ELEOTRIC MACHINE.

Patented March 20, 1906.

Application filed May 21, 1904. Serial N 209,000-

To all whmit it may concern Be it known that I, JOHN P. MALLETT, a

' citizen of the United States, residin at Madison, county ofDane, and State of isconsin, have invented certain new and useful Improvements in Dynamo-Electric Machines, of which the following is a specification.

My present invention relates to dynamoelectric machinery; and it consists in certain features of construction and arrangement of field-magnets therefor.

The points of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part ofmy present specification; For a. better understanding of my invention, however, reference may be had to the accom anying description and drawings, in which I ave described and illustrated one embodiment of my invention.

Of the drawings, Figure 1 is an elevation with parts broken awa and in section, showing a portion of a field-magnet. Fig. 2 is a erspective view showing a pole-piece, and

1g. 3 is an elevation of the pole-piece with portion in section taken at right angles to In the particular construction which I have illustrated in the drawin s the bod of the pole-piece 1 is formed oflaminae. he upper ends of the groups 2 of the laminae are beveled alternately in opposite directions and are cast into the cast iron or steel field yoke or ring 3. The laminae are secured to ether byanumber of bolts or rivets 4. 0st of the laminae composing each poleiece are notched'ign o posite sides adjacent t e armature end'of t e pole-piece, as indicated at 5. Bars 6', preferably formed out of some material, such as cast-iron, having a lower ma netic permeability than the laminated b0 y of the pole, enter the grooves formed in the opposite sides of the pole-pieces by the successive'notches formed in. the laminae. The

of the armature and are secured together by securing means, such as threaded bolts 7. To

forma passage for each bolt 7, certain of the laminae 8 are shortened, so that their lower ends terminate in the plane including the upper sides of the notches 5. This forms a assa e 01" channel 9 in the-armature end 0 the po e-piece extending transversely to the was of the armature of a width equal to the diameter of a bolt 7. The inner ends of thelaminae are curved, as shown, so as to be separated by a substantially uniform short airgap 10 from the outer surface of the armature 11. The inner edgesof the bars 6 may, however, be tangential to the circle of curvature of the inner ends of'the laminae.

With the construction described it is only necessary to machine or grind the portions of the bars 6 which come into contact with the laminae. The field-coils 12 (shown in Fig. 1) rest against and are held in place by the bars. To remove the field-coil, it isof course only necessary to unscrew the securing-nuts from the bars 7 and remove the bars 6. The bars 6 when formed of magnetic material havin a lower de ree of magnetic permeability t an the ho y of the ole-piece form desirable pole-tip ieces, as t ey give a fringed or graduated eld strength at the ed es of, the pole-piece, which is a very desirable feature, particularly in commutatingmachines.

The construction described is a reliable and efiioient one and by reason of its sim plicity can be manufactured at .a comparativel low cost. 1

While my invention may be advantageously employed, as shown, with pole-pieces having their outer ends cast into the field ring 'or yoke, it will of course be clearly understood that it may be embodied in constructions where the ole-pieces are separable from the ring or yol; member of a dynamo-electric machine.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. In combination, a pole-piece having.

grooves formed inopposite sides of its armature end, pole-tip pieces formed of material of different magnetic permeability from the pole-piece enterlng said grooves, slots or passages being formed in the armature end of sald pole-piece, and bolts for securing said some of the laminae of which are shortened pieces together passing through said passages.

e or are carried by the internal to form passages in the armature end of said pole-piece, and eest metel pole-tip pieces secured to the through said passages.

e. in combination, a field ring or yoke, a laminated pole-piece permanently secured thereto, some of the laminae composing the pole-pieces being shortened to form a passage in the armature end of said pole-piece, and coil-reteining pole-tip pieces secured to said pole-piece by a bolt extending through said passage. I

5. In combination, a laminated pole-piece, some of the laminae of which are shortened to form apessege adjacent the erineture end of said pole-piece, and mood-retaining device secured to seid poleiece by e'securing device extending throng said passage.

6. in combination, e pole-piece thebody of which is formed of laminae, some of which ere shortened to form e passage adjacent the polepiece by bolts extending F armature end of the pole-piece, and a polei tip piece secured to said pole-piece by a bolt located in said passage.

7., In combination, e pole-piece having slots or passages formed at it's armature end extending transversely to the armature-axis, pole-tip pieces, and means located in said slots or passages for securing said pole-tip pieces to the pole-piece.

8. In combination, a pole-piece having grooves or slots formed in its armature end extending transversely to the armature-axis, e coil-retaining device, and securing means therefor entering said rooves or slots.

In Witness whereof have hereunto set my hand this 16th day of May, 1904.

JOHN P. MALLETT Witnesses: l

H. L. MORRIS, A. J. BUENZLL' 

